The many documents found in different archives have provided new information on one of the more disregarded periods in the whole history of the Certosa. The historians believed that the monument had been left unattended especially during the 19th century. On the contrary, starting from the end of the 18th century, after the monks had left, the conservation of the whole monument, and especially the church façade, was taken into great consideration and its decay is to be ascribed to the unfavorable climate before that. In order to repair the already apparent damage and avoid its worsening, subsequent restoration work was undertaken (1817-1819, 1824-1827, 1833-1837, 1903-1927). Many of the pieces were substituted in the marble facing during these restorations. The knowledge of these substitutions is very important in studying the causes of the stone materials decay. Routine maintenance work was always assured during the period of minor activity, especially with the sealing of cracks and joints. No relevant restoration work was done after World War II, in spite of the increased decay, and the amount of documents and detailed information decreases.